Drying apparatus for coated objects

Abstract

A drying apparatus is provided for drying objects such as citrus fruit that has been coated with an aqueous coating such as wax. The apparatus includes a housing that is divided into four distinct zones, two each above and below a conveyor for conveying fruit through the dryer. An indirect fired heater is provided, and fans that circulate drying air at high velocity in a reverse air flow pattern. The housing of the dryer is constructed in a unique shape so each successive zone is alternately converging and diverging. With this arrangement, air is balanced in the treatment zones and passes over the fruit twice, first in one direction, and then in the other, to achieve even and complete drying.

We claim: 
     
       1. An apparatus for drying objects, said apparatus comprising: a housing defining a treatment area within said housing;   a conveyor for carrying said objects into and through said treatment area in said housing;   a heater for heating drying air to be circulated in said treatment area of said housing;   air circulating means for circulating drying air over said objects as said objects are conveyed through said treatment area;   said apparatus further characterized in that said treatment area is divided into four zones, a first zone on one side of said conveyor and adjacent an entrance end of said treatment area, a second zone on the other side of said conveyor and adjacent said entrance end of said treatment area, a third zone adjacent an exit end of said treatment area and on the same side of said conveyor as said second zone, and a fourth zone adjacent said exit end of said treatment area and on the same side of said conveyor as said first zone;   said air circulating means including a first fan means between said fourth and said first zones and arranged to draw air from said fourth zone and force that air into said first zone, said air circulating means further including a second fan means between said second and said third zones and arranged to draw air from said second zone and force that air into said third zone.   
     
     
       2. The apparatus of claim 1 wherein said housing is shaped to define said treatment area such that each successive zone is alternatingly converging and diverging in shape in the general direction of air flow therein. 
     
     
       3. The apparatus of claim 1 wherein said first zone is above said conveyor, said second zone is below said conveyor, said third zone is below said conveyor, and said fourth zone is above said conveyor. 
     
     
       4. The apparatus of claim 3 wherein said second zone is adjacent to and immediately below said first zone and is in pneumatic communication with said first zone through said conveyor and said objects on said conveyor, and said fourth zone is adjacent to and immediately above said third zone and is in pneumatic communication with said third zone through said conveyor and said objects on said conveyor. 
     
     
       5. The apparatus of claim 1 wherein an air distribution panel is disposed within said first zone and interposed between said first fan means and said conveyor. 
     
     
       6. The apparatus of claim 1 wherein an air distribution panel is disposed within said third zone and interposed between said second fan means and said conveyor. 
     
     
       7. The apparatus of claim 1 wherein said objects are fruit having an aqueous coating such as wax thereon. 
     
     
       8. The apparatus of claim 1 wherein said heater is in communication with one of said zones and heats supply air for introduction into that zone to maintain a desired temperature within said treatment area. 
     
     
       9. The apparatus of claim 8 wherein said one of said zones is the fourth zone, and said fourth zone also includes an exhaust vent to release from the treatment area a portion of the air circulating in the treatment area. 
     
     
       10. The apparatus of claim 9 wherein said apparatus is installed in a building and said vent is arranged to exhaust air outside of said building. 
     
     
       11. The apparatus of claim 1 wherein said heater is an indirect fired heater. 
     
     
       12. The apparatus of claim 11 wherein said apparatus is installed in a building and said heater exhausts heating exhaust gases outside of said building. 
     
     
       13. The apparatus of claim 1 wherein said apparatus is installed in a building, said heater includes a fresh air inlet, and said fresh air inlet is arranged to draw air into said heater from outside of said building. 
     
     
       14. The apparatus of claim 11 wherein said heater is arranged to maintain a temperature in the treatment area of up to a maximum of 95 degrees Fahrenheit. 
     
     
       15. The apparatus of claim 1 wherein said air circulation means is arranged to produce air flow over the objects on the conveyor between said first and second zones, and over the objects on the conveyor between said third and fourth zones, at a velocity of at least 1000 feet per minute. 
     
     
       16. The apparatus of claim 1 wherein said housing includes access panels to permit access to the interior of the treatment area. 
     
     
       17. The apparatus of claim 1 wherein said housing includes a layer of insulation.